On Tuesday, divers plunged into waters off Alexandria and explored the submerged ruins of a palace and temple complex from which Cleopatra ruled. They swam over the ruins that have been hammered into the sea by earthquakes and tsunamis more than 1,600 years ago.

According to the Associated Press, the international team is excavating one of the richest underwater archaeological sites in the world and retrieving artifacts from the last dynasty to rule over ancient Egypt before the Roman Empire annexed it in 30 B.C. Using advanced technology, the team is surveying ancient Alexandria’s Royal Quarters, encased deep below the harbor sediment, and confirming the accuracy of descriptions of the city left by Greek geographers and historians more than 2,000 years ago.

“It’s a unique site in the world,” said Franck Goddio, French underwater archaeologist and leader of the team.

The finds from along the Egyptian coast will go on display at Philadelphia’s Franklin Institute from June 5 to Jan. 2 in an exhibition titled “Cleopatra: The Search for the Last Queen of Egypt.” The exhibition will tour several other North American cities.

Tuesday’s dive explored the sprawling palace and temple complex where Cleopatra, the last of Egypt’s Greek-speaking Ptolemaic rulers, seduced the Roman general Mark Antony before they committed suicide upon their defeat by Octavian, the future Roman Empire Augustus. Dives have taken Goddio and his team to some of the key scenes in the dramatic lives of the couple, including Timonium, commissioned by Antony after his defeat as a place where he could retreat from the world, though he killed himself before it was completed.

“We’ve found many pharaonic objects that were brought from Heliopolis, in what is now Cairo,” said Ashraf Abdel-Raouf of Egypt’s Supreme Council of Antiquities. “So, the Ptolemaic rulers re-used pharonic objects to construct their buildings.”